The rectenna design on contact lens for wireless powering of the active intraocular pressure monitoring system

Abstract

This paper proposed a wireless power harvesting system with micro-electro-mechanical-systems (MEMS) fabrication for noninvasive intraocular pressure (IOP) measurement on soft contact lens substructure. The power harvesting IC consists of a loop antenna, an impedance matching network and a rectifier. The proposed IC has been designed and fabricated by CMOS 0.18 um process that operates at the ISM band of 5.8 GHz. The antenna and the power harvesting IC would be bonded together by using flip chip bonding technologies without extra wire interference. The circuit utilized an impedance transformation circuit to boost the input RF signal that improves the circuit performance. The proposed design achieves an RF-to-DC conversion efficiency of 35% at 5.8 GHz.

Wireless Communication and Power Harvesting in Wearable Contact Lens Sensors

“…As the far-field radiation pattern shows in Fig. 4(d), a single loop antenna could be highly directional [120].…”

“…For an electronic contact lens, the magnetic loop antenna is suitable as the receiving antenna since the size of the designed antenna is generally constrained to be less than a tenth of the wavelength of the electromagnetic wave. The frequency applied on electronic contact lenses for loop antenna varies from 13.56 MHz High Frequency (HF) band to 5.8 GHz microwave band [94,102,112,117,[119][120][121]. Fig.…”

Compact rectenna based on a fractal geometry with a high conversion energy efficiency per area

“…The rectennas can also be an alternative in situations where batteries need to be replaced periodically and the device location makes the replacement of the batteries infeasible by economic reasons and/or by involving significant risks to human life. In recent years, commercial application using rectennas have been proposed, such as a contact lens for intraocular pressure monitoring [4,5] and an air pollution smart sensor [6], demonstrating the viability of wireless power transmission with rectennas.…”

Antenna and coil design for wireless signal detection and charging of embedded power active contact lens

“…Pandey et al [2] fabricated a contact lens with a single LED display powered by 2.4GHz. Cheng et al [3] presented a 5.8GHz rectenna design focusing on increasing efficiency by using high Q passive components to impedance match the antenna to the rectifier. The drawback of RF scavenging is that the levels of energy present in the environment are small.…”